(HILLSBOROUGH, N.C.) — The person who reported this weekend’s apparent arson attack and graffiti vandalism at a county Republican Party headquarters in North Carolina told police: “They threw some sort of firebomb through the window. … I can smell smoke.”

The 911 call about damage to the GOP’s Orange County office in Hillsborough was released Monday with some parts redacted and the caller’s voice deliberately distorted to protect the person’s identity, Hillsborough police said. Law enforcement is still investigating the crime and urging anyone with information to come forward.

The suspected firebombing happened between midnight Saturday and the time of the call at 8:54 a.m. Sunday, police believe.

“Someone has firebombed through the window of the Republican Party next to me and sprayed all over the side of my building: ‘Nazi Republicans leave town or else,'” the 911 caller, who police said owns a business nearby, told police Sunday morning.

The caller attributed a smell at the site to an “incendiary device.”

“They threw some sort of firebomb through the window because it smoked up under the porch and all around the window frame,” the caller said. “I can smell smoke, so obviously it went out on its own or didn’t work well, but it is some sort of incendiary device.”

Police said “a bottle containing flammable material was thrown through a front window” of the GOP office, damaging the inside and some furniture “before going out on its own.” Graffiti was spray-painted on the side of a building next door.

Hillsborough Mayor Tom Stevens called the apparent attack on the building a “reprehensible act.” He added, “I’m extremely appreciative for everybody who is using this as an opportunity to pull our community together, rather than promote division.”

White House Press Secretary Josh Earnest said Monday of the apparent attack, “There is no justification for the use of violence to advance a political agenda.”

The town’s police said they are working with the federal and state bureaus of investigation, the Bureau of Alcohol, Tobacco, Firearms and Explosives and the Orange County Sheriff’s Office. The Secret Service also is supporting the investigation, the police said.

A law enforcement source told ABC News that evidence has been sent to the FBI laboratory in Quantico, Virginia, for analysis.